Ellipsograph



Mach 31, 1959 H. A. KROENLEIN 6 ELLIPSOGRAPH Filed Dec. 28, 1954 3mvENTOR HSMZYA. AEOEA/LEW BYOZVMM ATTORNEY Uited States Patent ELLIPSOGRAPH Henry A. Kroenlein, Los Angeles, Calif. Application December 28,1954, Serial No. 477,963

1 Claim. or. 33-31 The present invention relates to improvements ingeometrical instruments, and more particularly to improve ments inellipsographs.

Heretofore, the art has soughtto provide devices of this type whichwould be easy to assemble and adjust to the conditions of operation,would be easy to orient precisely with regard to the surface on whichthe geometrical figure was to be drawn, and would function smoothly andreadily in operation. In various efforts to provide devices of thischaracter having these desirable features, it has been proposed toconstruct ellipsographs having a scriber beam guided by a pair of guidemem bers disposed at right angles toeach other after the manner of themajor and minor axes of the ellipse to be drawn. However, it was foundin practice that devices having such a construction were difficult tooperate due to the friction between the moving parts and would oftenstick or bind in use. In an effort to remedy this difficulty, theworking parts were loosened; but the resulting play or lost motionrendered the devices inaccurate. In an effort to mount the scriber beamfirmly to the guide means, it was proposed to clamp it or bolt it tosliding guide members; but a device constructedaccording to thisprinciple was diflicult to assemble. Moreover, in a device having thescriber means clamped to the guide means, it was found that the markeror scriber did not properly contact the surface on which the geometricalfigure was to be drawn, but tended to ride above that surface or beartoo heavily upon that surface. Finallyfin an effort to orient anellipsograph nicely with regard to the major and minor axes of theellipse to be drawn, it was proposed to provide indicator lines on thebase of the ellipsograph disposed at right angles to each other, whichlines could be laid over the respective axes of the ellipse to orientthe instrument. However, it was found that in practice such indicia weredifiicult to place precisely with regard tothe axes, with the resultthat the ellipsograph was frequently misaligned in use. Although manyattempts were made to overcome the foregoing difiiculties and otherdisadvantages, none, as far as I-am aware, wasentirelysuccessful whencarried into practice commercially on an industrial scale.

Accordingly, it is an object of the present invention to provide anellipsograph in which frictional forces tending toward misalignment ofthe scriber will be reduced to a minimum.

Another object of the invention is to provide an ellipsographwhich willbe easy to assemble and disassemble.

The invention also contemplates providing an ellipsograph in which themarker or scriber will readily adjust to the surface on which theellipse is to be drawn so as tobear on that surface with the desiredpressure at all times.

A still further object of the; invention is the provision of anellipsograph having locator means for orienting it relative to the axesof the ellipse to be drawn, with ease and precision.

Finally, it is an object of the present invention to provide anellipsograph which will be simple and inexpensive in construction, andrugged, durable and accurate in operation.

Other objects and advantages will become apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

Figure 1 is a perspective view of an ellipsograph according to myinvention;

Figure 2 is an isometric exploded detail view of a portion of theellipsograph shown in Figure 1;.

Figure 3 is a plan view of a fragment of an ellipsograph according to myinvention, showing the locator means in various adjusted positions; and

Figure ,4 is a front elevational view of an ellipsograph according tothe invention.

Referring now to the drawings in greater detail, I have shown inperspective in Figure 1 an ellipsograph indicated generally at 1,comprising a base member 3 which may desirably be of a transparentplastic carrying at its forward edge a pair of upstanding stanchions 5which bear between them a round bar 7 spaced above and parallel to basemember 3. Spaced rearwardly of b arf7 is a pair of fixed posts 9 and 11upstandingfrom base member 3 and serving as fixed axes for a pair oflinks 13 and 15 pivotally mounted on the upper ends of the posts.

i At their. outer endsylinks 13 and 15 are pivotally connectedat spacedpoints to a superposed bar'17 which at its outer end carries upright pin19 lying beyond the points of pivotal connection of bar 17 to links 13and 15.

Mounted slidably and rotatably on round bar 7 is a collar 21, perhapsbest shown in Figure 2. Collar 21 will be seen to be of generallytubular form having an interior surface complementary to the outercylindrical surface of round bar 7 to permit easy sliding therealong androtation therea-bout. Collar 21 is provided with a central offsetportion 23 which extends toone side centr'allythereof and carriers pin25 which willbe upright when the ellipsograph isin use. k

A scriber beam 27 comprising a pair of spaced apart round bars includesa marking end 31 comprising a collar 33 having a thumb screw 35screW-threadedly extending therethrough for the reception and retentionof marking device 37, which may be in the form of a pencil or pen orstylus or other marking implement. Slidably mountedon the two round barscomprising scriber beam 27 is a first slide block 39 provided with fourholes therethrough: two for the reception of the two bars comprisingscriber beam 27, a round vertical hole 41 for the reception of round pin25 when in upright position, and a laterally disposed hole for thescrew-threaded reception of thumb screw 43 whichselectively locks slideblock 39 to aldesired position along scriber beam 27. Rearwardly of the"first slide block with regard to the marking device is a second slideblock 45 carried on scriber beam 27- for sliding movement along the tworound bars through a pair 'of holes in this slide block and having around vertical hole 47 for the reception of round pin 19 and a Theellipsograph of the invention is also provided with indicia beam forlocating it relative'to the major and minor axes of the ellipse to bedrawn, comprising a beveled straight edge 51 adapted to be laid exactlyalong the major axis of the ellipse and recessed as at 52. Inwardly ofrecess 52in base member 3 is a hole 53 adapted to overlie the minor axisof the ellipseto be drawn. As best seen in Figure 3, a lever 55' ispivoted at 57 to base member 3 and carries at its outer end a locatorpin 59 which extends below the level of the lower surface of base member3, as seen in Figure 4.

It should be particularly noted that pivot 57, hole 53 and post 9 are inalignment and all overlie the minor axis of the ellipse to be drawn. Itshould also be noted that straight edge 51 and pin 25 are in verticalalignment and both overlie the major axis of the ellipse to be drawn. Tothis end, the axis of pin 25 is spaced outwardly from the axis of collar21 the same distance as the axis of rod 7 is spaced inward from straightedge 51. It should also be noted, as best seen in Figure 4, that pin 25is substantially longer than pin 19 and terminates downward at a lowerpoint than does pin 19. It should also be noted that pins 19 and 25terminate upward in a common horizontal plane.

The ellipsograph according to my invention may be assembled as follows:A marking device 37 may be inserted in collar 33 and thumb screw 35turned in to lock it in place. Pin 25 may then be turned into verticalposition about bar 7 and pins 19 and 25 inserted in holes 47 and 41,respectively.

The device of my invention may be used as follows: After having drawnthe two axes of the ellipse and indicated the desired major and minorradii, locator pin 59 may be pricked into the surface on which theellipse is to be drawn at the intersection of the two axes. The devicemay be roughly aligned by lining up the major axis and straight edge 51;but fine alignment is made by swinging lever 55 back and forth aboutpivot 57 and locator pin 59. Since 59 remains fixed at the intersectionof the axes, it will be seen that swinging movement of lever 55 tends tomove the ellipsograph back and forth, so that hole 53 will move from oneside to another of the minor axis. At the same time, straight edge 51will undergo a slight movement relative to the major axis. When theellipsograph is nicely oriented, thumb screws 43 and 49 may be loosenedso that scriber beam 27 is free to move in slide blocks 39 and 45. Thescriber beam may then beturned parallel to the major axis and, markingdevice 37 set on themark for the major radius and thumb screw 49tightened. The scriber beam may then be turned 90 degrees and markingdevice 37 set on the mark for the minor radius and thumb screw 43tightened. One-half of the ellipse may then be drawn, the instrumentswung 180 degrees about the locator pin 59, and the other half of theellipse drawn. It will be appreciated that during the drawing of theellipse the pin 19 will move in a vertical plane containing the line ofthe minor axis, which plane also contains the center of hole 53 and theaxis of post 9.

It will thus be seen that I have provided an ellipsograph in whichfriction is reduced to a minimum. Inasmucli as rectilinear slidingmovement occurs at only one point in my ellipsograph, along bar 7, thereis no opportunity for rectilinear sliding surfaces disposed at angles toeach other to cause the device to stick orbind.

It will also be seen that I have provided an ellipsograph that isextremely easy to assemble and disassemble. It is necessary merely toslip scriber beam 27 over the pins 19 and 25. Tothis end, it will benoted that pin 25 is rotatable about bar 7, but that the axes of pin 25and bar 7 are skew. Thus, the offset afforded by portion 23 insures thatwhen pin 25 is manipulated for insertion into hole 41, any lateralmovement of the upper end of the pin will be accompanied by a muchsmaller angular displacement than if the axis of pin 25 intersected theaxis of bar 7 and pin 25 were mounted radially relative to bar 7. Thus,pin 25 may be manipulated without substantially altering its anglerelative to hole 41, with the result that it may be inserted much moreeasily in hole 41. v

It will also be seen that I have provided an ellipse graph which can beeasily located precisely with respect to theaxes of ellipse to be drawn.It was heretofore necessary to attempt bodily to skid the ellipsographs6f the prior art into position with their indicia lines exactly'overlying the axes of the ellipse to be drawn. However, it will be seenthat by manipulation of lever 55, which in this instance functions as asecond-class lever, regulated movements of the lever produce fineadjustment of the ellipsograph relative to the axes, and that in thecase of hole 53, it is a good deal easier to center a line in anoscillating hole than to determine when two lines appear to overlie.

It will also be seen that I have provided an ellipsograph in which thepressure with which marking device 37 bears on the surface on which theellipse is to be drawn, is nicely regulated. As best seen in Figure 4,scriber beam 27 rests on the upper part of bar 17 through slide block45. Pin 25 extends substantially farther down than pin 19, so that slideblock 39 thereabout never rests on portion 23 but always slides up anddown on the pin. There will inevitably be a slight amount of playbetween pin 19 and block 45, with the result that marking end 31 enjoysa slight vertical adjustability, as seen indotted lines in Figure 4 atthe left thereof, the dotted lines to the right thereof being omittedfor the sake of clarity.

Finally, it will be seen that I have provided an ellipsograph which iseasy and inexpensive to manufacture and assemble and is sturdy, durableand accurate in operation.

Although the present invention has been described in conjunction withpreferred embodiments, it is to be understood that modifications andvariations may be resorted to without departing from the spirit andscope of the invention, as those skilled in the art will readilyunderstand. Such modifications and variations are considered to bewithin the purview and scope of the invention and appended claim.

, I claim:

7 An ellipsograph comprising a horizontal planar base having a referenceedge alignable with the major axis of the ellipse to be drawn, a scriberbeam, guide means, means affixed to said base parallel to said edgepivotally mounting said scriber beam on said guide means, said pivotalmounting means being movable rectilinearly along said guide means,locator means adjustably positionable on said base at the intersectionof the major and minor axes of the ellipse to be drawn, a pair of linksmounted for rotation on said base about spaced axes fixed relative tosaid guide means, and a bar pivotally connected to each said link at apoint spaced from its respective axis and to said scriber beam at athird point spaced from said pivotal mounting means, one of said spacedaxes defining with said locator means a first line perpendicular to theline of rectilinear movement of said pivotal mounting means along saidguide means coincident with the minoraxis of the ellipse to be drawn,reference means (in said base on said first line to align said firstline and the minor axis, said third point moving in a vertical planecontaining said first line.

References Cited in the file of this patent OTHER REFERENCES Ke'ow'n andFaiie's: Mechanism, published by Me- Gawain Book 30., me, New York,1931, pages 11-12.

